1. Field of the Invention
Exemplary embodiments of the present invention relate to a clock and data recovery (CDR) apparatus with adaptive optimum CDR bandwidth estimation by using a Kalman gain extractor.
2. Discussion of the Background
The input jitter of a clock and data recovery (CDR) can be modeled as the sum of the accumulation and periodic jitter. The periodic jitter does not accumulate over time and has bounded variance in general.
Data-dependent deterministic jitter is a subset of the periodic jitter. The accumulation jitter, on the contrary, is unbounded in nature and increases indefinitely with time, thus a CDR has to track it for bit-error-free operation.
The analogy between the Kalman filter and a bang-bang (BB) CDR is utilized for the analytical minimum bounds of the mean squared phase error of a BB CDR circuit under the condition of random phase tracking.